Elimination of inhibitors of alkaline phosphatase from 2-amino-2-methyl-1-propanol.

When 2-amino-2-methyl-1-propanol buffer solutions are extracted with chloroform, impurities inhibiting alkaline phosphatase are selectively removed and this source of variation is thereby greatly decreased. We also studied the effect of adding zinc sulfate to this buffer. A combination of chloroform extraction and zinc sulfate, added to give concentrations from 5 to 10 mumol/L, results in buffer of high and consistent quality. The alkaline phosphatase activities of 12 reference sera of different origin were determined with use of the purified buffers. Those sera, which closely resembled human serum in terms of alkaline phosphatase isoenzyme composition, behaved similarly to human serum. Use of such control sera is strongly recommended.